Incandescent electric lamp.



PATENTED MAY 19, 1908.

M. D. JONES. INGANDESUENT ELECTRIC LAMP.

APPLIGATIQN FILED APR. 30, 1907.

[AW/WYUR.

A TTOR/VE V5 UNITED STATES j PATENT oFFroE.

MARSHALLD. JONES, oF DAVENPORT, IOWA, ASSIGNOR OF ONE-FOURTH TO Louis H.SMITH,

' oF DAVENPORT, IOWA.

Specification of Letters Patent.

Patented May 19, 1908.

Application filed April 30, 1907. Serial No. 371,064.

To all whom it may concern:

Be it known that I, MARSHALL D. JoNEs, a citizen of the United States,residing at Davenport, in the county of Scott and State of Iowa, haveinvented a new and useful Incandescent Electric Lamp, of which thefollowing is a specification.

This invention has reference to improvements in incandescent electriclamps, and its object is to provide a lamp having greatlight= diffusivepower.

The invention consists essentially in forming the lamp bulbsubstantially hemispherical in shape, with a dished upper surface ofsubstantia ly frusto-conical shape, with the filament entering throughthe center of the dished upper surface and so formed as to constitute abroad light-giving unit extending in a direction perpendicular to theaxis of the body portion of the lamp and entering said body portion to agreater distance than does the dished upper surface. The dished portionof the lamp has its outer surface silvered to constitute a reflectingmirror, while the filament is sufliciently removed therefrom to causethe light to be reflected over a large area.

Lamps constructed in accordance with the present invention areparticularly adapted for desk lamps, for show windows, for ceilinglamps, and for decorative purposes. In fact, they may be used whereverit is desirable to throw a diffused beam of light in some particulardirection. These lamps are also particularly adapted for clusters, wherethe light coming from an. ordinary lamp is partially lost or absorbed. 1

Bulbs constructed in accordance with the present invention have adiffusive area up to one hundred and eighty degrees, or possiblysomewhat less, beyond which zone no light at all passes from the lampconsequently, they give a materially greater amount of li ht within thecircumscribed area of diffusion than does an ordinary lamp, and inaddition to this the base of the lamp is not inter osed in any manner inthe light area of the amp. The invention will be fully understood fromthe following detailed description taken n connectlon with theaccompanying drawngs formmg part of this specification, in wh1ch,- 1

Figure 1 is a side view of an incandescent electrlc lan p constructed inaccordance with my invention; Fig. 2 is a central section through thesame, with the base shown in elevation; and Fig. 3 is a central section,

showing a modified form of the reflector.

Referring to the drawings, there is shown 4 an incandescent electriclamp bulb, the body 1 of which is approximately hemispherical inoutline. The socket end or cap portion 2 of the lamp bulb is dished inthe form of a shallow, inverted, frusto-cone integral with the bodyportion 1, and at its center carrying the screw-base 3 of the ordinaryEdison type, as shown, or of any other desired type. The base end of thelamp is provided with the usual glass support 4 for the filament 5.

It will be observed that this filament conforms in a manner to the shapeof the body 1 of the lamp. The filament may be of the spiral form, andis so shown, but the spiral is condensed in the direction of the centralaxis of the lamp so that the filament spreads laterally butis in themain quite close to the support 5 In order that the filament may besecurely supported within the bulb, suitable anchors 6 may be provided.

It will be observed that the filament is carried within the body portion1 entirely beyond the zone occupied by the frusto-conical base-carryingportion, so that light from the filament reaches every portion of thereflecting surface, and, consequently, the diffusive effect of thisreflecting surface is greatly enhanced. It will be further observed thatthe glass support 4 projects beyond the point of greatest projection ofthe base carrying portion 2 into the body portion 1, whereby thefilament while spread laterally with relation -to the axis of the bodyportion 1, is still located well beyond the base-carrying ortion 2 andin no case is it brought into 0 ose relation thereto.

On the exterior surface of the dished portion'2 of the lamp bulb thereis provided a. layer 7 of a suitable material for forming a reflectingsurface on the exterior of said portion 2, which reflecting surface,however, is ad- 'acent to the glass so that it will reflect all lightcoming from the filament 5 to the portion 2 of the bulb in a directiontoward the body portion 1 and throu h the same outward away from saiddishe portion 2. This reflecting surface may be formed of the ordinarymercurial silvering compound used on lookin glasses or it may beproduced in any desire way. j; 1

It will be seen thatthe light element, consisting of the filament 5,covers a considerable area with relation to the axis of the lamp, and

this lighttelement is backed by a reflector,

also of considerable area and so shaped or formed as to spread the lightrays.

Now, let us assume that the lamp is in the position illustrated in thedrawing, that is, with the base uppermost and the body portion directeddownward. It is known that the intensity of illumination will be thegreatest in. a downward direction from the filament and will graduallygrow weaker up to a horizontal plane and beyond. Now, with thereflecting surface formed as shown, those rays of light which wouldordinarily pass upward above the horizontal plane are caught by thereflector and thrown outward at various angles from the horizontal planeand downward. These reflected rays are added to or'reinforce the weakerhorizontal light emanations from the filament so that the photometricvalue of the lamp will be approximately equal throughout the light-givmzone. I

dt will be seen that lamps of the character described are particularlyuseful where it is desired that a rather diflused light shall be thrownin one general direction. For instance, lam s of thischaracter areparticularly useful for cluster chandeliers, for in such casesnot onlyis there a greater amount of light 1n the direction desired, but theartistic effect is much enhanced. For show-window or show-caseillumination, for art gallery illumination, for cornice illumination,for reading lamps, or for house illumination where it is desirable thatthe light be in the main directed downward and sidewise, these lamps areparticularly adapted, while for' decorative purposes the brilliant baseof the lamp will add very materially to the esthetic eflect.

.lln Fig. 3 the reflector is shown in the form of a shallow, invert,frusto-cone 2 with a central reentering frusto-cone 8, at the centralplateau whereof is the screw-base 3.

This form will act in a similarmanner to the form shown in the otherfigures, but will also give more diffusion of light.

I claim 1. An incandescent electric lamp having a substantiallyhemispherical body portion, a base portion provided with walls of invertfrusto-conical shape and having a reflecting surface, and a filamententering the body of the lamp through the center of the base portion andextending in a direction substan tially perpendicular to the axis of thebody portion and located in the latter at a point beyond the point ofgreatest extension of the base carrying portion into the body portion.

2. An incandescent electric lamp comprising a substantiallyhemispherical body portion, a base portion provided with walls of invertfrusto-conical shape and having a reflecting surface, a terminal basecarried directly by the center of said base portion, a support carriedby said base and entering centrally into the body portion beyond thepoint of greatest extension of the base portion therein, and a filamentcarried by said central support and in the form of a substantially flatspiral extending in a direction perpendicular to the' axis of the bodyportion.

3. An incandescent electric lamp having an invert, frusto-conical basewith the central portion formed with a reentering frusto-cone, andprovided with a reflecting surface.

4. A light-reflecting and diffusive element comprising a frusto-conicalreflector having its central portion in the form of a renteringfrusto-cone.

In testimony that I claim the foregoing as my own, I have hereto aflixedmy signature in the presence of two witnesses.

MARSHALL D. JONES.

Witnesses S. H. SMITH,

C. E. LAMB.

